There's no way in hell you finished every quest, collected all the skill books, and explored every location in 32 hours. Pure bullshit.
OT: This is pretty old and you've probably made your decision, but I think it somewhat comes down to the setting/style you prefer. I am a huge fan of post-apocalyptic wastelands and i'm not big into medieval fantasy settings with castles and stuff, so naturally I liked Fallout more. Not saying Oblivion wasn't a good game, though; being a stealthy marksman was incredibly fun.